1. Field of the Invention
The present invention relates to a cleaner for removing toner that adheres to the surface of a transfer drum installed in copy machine and preferably installed in a full-color copy machine.
2. Description of the Prior Art
In full color copiers, a single copy is produced by sequentially developing several images formed on a photoconductive drum and sequentially transferring said developed images onto the same copy paper sheet. Thus, the copy sheet is maintained in touching contact with the photoconductive drum through several copy processing cycles. The developed image on the surface of the photoconductive drum is obtained by adhering toner to an electrostatic latent image formed on the surface of said photoconductive drum, and the electrostatic latent image is obtained by charging the entire surface of said photoconductive drum by means of a corona charger, and then exposing an original document image on the surface of said photoconductive drum.
The surface area of the photoconductive drum generally is greater than the surface area of the maximum permissible size original document. The surface of the photoconductive drum, therefore, has sections at both ends and at the front and back which are not exposed to light and to which large quantities of toner adhere during the developing process. After the developing process, the toner adhering to the aforesaid unexposed sections is transferred to the transfer drum (comprising the surface of which is formed by a dielectric film or grid of polyester or the like without an electrically conductive substrate) which comes into touching contact with the surface of the photoconductive drum, thereby soiling said transfer drum and causing surface soiling of the copy sheet (hereinafter referred to as "toner soiling").
Accordingly, copiers are provided with cleaning devices to prevent the occurrence of the aforesaid disadvantages. An example of a conventional cleaner is the air suction type cleaner which uses a fur brush. More specifically, toner is scraped off by an insulated brush roller (fur brush) disposed so as to be in contact with the rotating region of the transfer drum, said scraped toner being removed by suction provided by a high-suction capacity blower. In addition to the aforesaid construction, a discharging brush is disposed opposite the aforesaid brush roller within the transfer drum, said discharging brush controlling the deformation of the drum in contact with the brush roller as well as discharging the interior of the transfer roller during the toner scraping process.
In conventional type cleaners as described above, however, the construction greatly increases the size of the device due to the reliance on the cleaning capability supplied by the suction capacity of the blower, which also results in the disadvantages of increased copier size and cost, noisier operation, and dispersion of dust.
In addition, the discharging brush on the inside of the transfer drum improves cleaning capacity somewhat by weakening the electrical attraction of the toner electrostatically attracted to the surface of the drum. In the previously described example of a conventional device, however, adequate cleaning capability is not realized because the combined action of the cleaner and the discharging brush is inadequate.